Host defense, dendritic cells and the human lung

摘要: textabstractHost defense mechanisms protect the body against microorganisms and other foreign structures. These can be divided in nonspecific, or innate, and specific, or acquired, immunity. In both branches of immunity the several types leukocytes (white blood cells) play a dominant role. Nonspecific comprises natural barriers that against invading microorganisms, complement system, various of white cells including granulocytes, monocytes, macrophages and natural killer are able to neutralize foreign material by phagocytosis and/or killing. The consist the epithelial surfaces body, such as skin bronchial epithelium. In lung, junctional complexes between epithelial physically prevent invasion microorganisms. addition, particles removed from respiratory tract "tapis roulant": the mucus film propelled towards oropharyngeal cavity cilia cells. not only serves vehicle for particle transport, but also contains antibacterial antiviral proteins. Specific immunity involves recognition structures (antigens), the discrimination self non-self, generation of immunologic memory. A crucial step initiation an immune response is presentation antigens stimulation T Cells capable of antigen-presentation called antigenpresenting cells (APC) comprise macrophages, B in particular dendritic (DC). Recognition presented antigen T cell costimulatory signals APC result in proliferation, cytokine production change marker expression T cell. thereby regulate activation effector such as 8 (that produce antibodies), macrophages. directed eliminate antigen.